title: Dilution effect in bovine tuberculosis: risk factors for regional disease occurrence in Africa.
abstract: Changes in host diversity have been postulated to influence the risk of infectious diseases, including both dilution and amplification effects. The dilution effect refers to a negative relationship between biodiversity and disease risk, whereas the amplification effect occurs when biodiversity increases disease risk. We tested these effects with an influential disease, bovine tuberculosis (BTB), which is widespread in many countries, causing severe economic losses. Based on the BTB outbreak data in cattle from 2005 to 2010, we also tested, using generalized linear mixed models, which other factors were associated with the regional BTB presence in cattle in Africa. The interdependencies of predictors and their correlations with BTB presence were examined using path analysis. Our results suggested a dilution effect, where increased mammal species richness was associated with reduced probability of BTB presence after adjustment for cattle density. In addition, our results also suggested that areas with BTB infection in the preceding year, higher cattle density and larger percentage of area occupied by African buffalo were more likely to report BTB outbreaks. Climatic variables only indirectly influenced the risk of BTB presence through their effects on cattle density and wildlife distribution. Since most studies investigating the role of wildlife species on BTB transmission only involve single-species analysis, more efforts are needed to better understand the effect of the structure of wildlife communities on BTB dynamics.
authors.affiliation: Resource Ecology Group, Wageningen University, Droevendaalsesteeg 3a, 6708PB Wageningen, The Netherlands. zheng.huang@wur.nl
authors.forename: Zheng Y X
authors.initials: ZY
authors.lastname: Huang
authors.forename: Willem F
authors.initials: WF
authors.lastname: de Boer
authors.forename: Frank
authors.initials: F
authors.lastname: van Langevelde
authors.forename: Chi
authors.initials: C
authors.lastname: Xu
authors.forename: Karim
authors.initials: K
authors.lastname: Ben Jebara
authors.forename: Francesco
authors.initials: F
authors.lastname: Berlingieri
authors.forename: Herbert H T
authors.initials: HH
authors.lastname: Prins
mesh_terms: D000349:Africa / Q000453:epidemiology; D000818:Animals; D000835:Animals, Wild / Q000145:classification / Q000502:physiology*; D002020:Buffaloes / Q000502:physiology; D002417:Cattle / Q000502:physiology; D004196:Disease Outbreaks; D006801:Humans; D009163:Mycobacterium bovis; D011156:Population Density; D012044:Regression Analysis; D012307:Risk Factors; D013045:Species Specificity; D014380:Tuberculosis, Bovine / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission*
keywords: African buffalo; amplification effect; cattle density; greater kudu; previous infection status; wildlife